Photofinishers customarily employ one or more quality control tools, typically in the form of calibrated first-generation camera-original negatives that contain reference portrait images, to make comparison measurements or observations in order to "fine tune" the operation and performance of various pieces of photofinishing equipment. (These calibrated camera-original negatives have come to be referred to as "Shirleys", named after the model photographed during the initial production many years ago).
Because of the contents of these camera-original reference negatives must be specified to extremely high standards, the process conventionally employed to produce them is expensive, labor intensive and time consuming. Factors which contribute to the arduous task of producing each camera-original negative include that the model and professional photographer must be available for an extended period of time (on the order of weeks to sometimes months). Associated with the use of a live model is the need for the continued services of a scene stylist in order to ensure the photogenic quality of the portraits. In this regard it should be noted that it is substantially impossible for even the most professional of models to maintain the same facial expression and body attitude (even with the assist of ergonometric devices) for the hundreds of exposures that make up a typical one of repeated photographic sessions. As a consequence, cosmetic and postural non-uniformities can be expected to occur in any given batch of product control tool negatives produced using current methods.
Unforeseen circumstances may also arise wherein the model originally chosen may become unavailable at some point prior to the completion of the production of the required number of product negatives, in which case a different model may have to be substituted. This substitution of one model for another also adversely affects the cosmetic uniformity of the product control tool negatives.
Additional factors encountered using the conventional method result in sensitometric non-uniformities in the product control tool negatives. These factors include, but are not limited to, the fact that the studio lighting used in the photography of the live model is complex, employing sidelights, keylights, gelatin color filters, etc., all of which are subject to performance variations, especially considering the extended time frame to produce large quantities of product negatives.
For the purpose of clarity throughout this document, definitions of the following terms as they will be used throughout this discussion are given below.
The term "negative" will refer to a camera exposure onto a film type from which photographic paper prints are normally produced.
Generally speaking, the photographic terms "positive" and "transparency" are interchangeable. For the sake of clarity, in this discussion the term "positive" will be reserved to mean a camera-original exposure onto a reversal film type, from which photographic paper prints are not normally produced, but which are usually viewed via projection.
The term "transparency", will be reserved to mean, specifically, that positive image which is digitally-generated onto a reversal photographic film type, or other non-photographic (e.g. thermal) medium, using a digital output recording device, and which is intended to be backlit and photographed to produce "second-generation camera-original" exposures (defined below), whether onto a negative or positive (i.e., reversal) film type.
The term "first-generation camera-original" will refer to a photographic exposure that is created in the usual manner, using a conventional camera to photograph a live scene. This camera exposure may be photographed onto either a negative or a positive film type.
The term "second-generation camera-original" will refer to a photographic exposure that is created using the method embodied within the present invention wherein a transparency produced by a digital output recording device is backlit and photographed using a conventional camera. As with a first-generation camera-original exposure, a second-generation camera-original exposure may also be photographed onto either a negative or a positive film type.
The term "primary film type" will refer to that film type onto which first-generation camera-original photographs that are intended to be photodigitized and sensitometric exposures that are intended to be photodigitized are exposed.
The term "product film type" will refer to that film type onto which second-generation camera-original product control tool photographs of a backlit digitally-generated transparency and first-generation camera-original verification photographs are exposed.
Since both first-generation and second-generation camera-original exposures may be produced on either a negative or positive film type, the term "photograph" will be used to avoid the cumbersome phrase "negative (or positive)" throughout the document.
The term "primary metric" will be used as an abbreviation for the more cumbersome phrase "primary digital image data metric."
The term "target metric" will be used as an abbreviation for the more cumbersome phrase "secondary, target digital image data metric."
The term "develop" will refer to the photochemical processing of an exposure, whether the exposure was created via a camera, a sensitometer or a digital output recording device.
The term "Color Chart" will refer to a physical chart comprised of approximately one hundred samples, possibly of paper, corresponding to various colors encountered in real life.
The term "Neutral Scale Chart", abbreviated as (NSC), will refer to a physical chart comprised of approximately fifty samples of spectrally non-selective (i.e., neutral) materials, possibly of paper, of discrete lightness/darkness values.